Grammar
Activities
Games
Grammar
The grammar for the Past Simple and Present Perfect is very clearly explained at these blogs:
Past Simple:
http://www.perfect-english-grammar.com/past-simple.html
Present Perfect:
http://www.perfect-english-grammar.com/present-perfect.html
In addition, you could view the following video that explains and demonstrates step-by-step the use and differences between these tenses.
Please, check out the links in the Activities and Games below. It is an effective and enjoyable way to practice grammar.
Activities
http://www.helpforenglish.cz/article/2005120403-present-perfect-vs-past
http://www.perfect-english-grammar.com/past-simple-present-perfect-4.html
http://www.englishpage.com/verbpage/verbs5.htm
Games
http://www.englishmedialab.com/GrammarGames/perfectpast/spin%20wheel%20present%20past%20tenses.html
http://a4esl.org/q/f/z/zz29bms.htm
http://www.eslgamesplus.com/present-perfect-vs-past-tenses-rally/
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